**6. Histopathological effects of insecticides**

Pesticides have been widely used from past to present so that food production in the world is not affected by external factors. The most common use in the world is seen in the United States, and almost 15 billion dollars are spent annually for the pesticides [62, 63] and the most common of them is the herbicide glyphosate [62, 64]. Besides their use for sectoral beneficial results, they cause many metabolic disorders and lead to even death, especially due to their intake and absorption into the living body in various ways. OP compounds [65] are responsible for half of the deaths by inhibiting the acetylcholinesterase enzyme (AChE) in the central and autonomic nervous systems, lungs and neuromuscular junctions [62, 66, 67]. AChE inhibition increases cholinergic activity in both the central and peripheral nervous systems. Loss of consciousness, diarrhea, bronchospasm, paralysis and vomiting are the most typical symptoms of poisoning [62, 68], and death can occur as a result of respiratory failure [69, 70]. The toxicity of the substances taken into the organism, its chemical

structure, the human resources involved in the poisoning event and the quality of the institution providing medical support affect the mortality rate [71]. Almost half of the patients who are affected by pesticides and apply to the hospital are intubated due to their symptoms and receive ventilation support. Approximately 23–50% of patients in this condition die [72, 73]. The way to diagnose a significant part of the diseases and to obtain sufficient information about clinicopathological parameters is performed by assessing the samples taken from the organism in diseases or suspicious cases. In addition to determining the morphological characteristics of the tissues taken in this process, the role of scientists and especially the contributions of histopathologists in this field are undeniably important in evaluating and interpreting from different scientific dimensions also by using the latest developments in which science has evolved [74]. Histopathological changes are associated with complex biochemical and physiological responses to any stressor. Although histopathological parameters are not highly specific and do not provide quantitative information, they are popular biomarkers for environmental pollution [75]. The histopathological studies, one of the most promising areas for assessing animal health and response to different chemical species, include various studies that show generally cellular differences between control and pesticide-exposed animals [76]. Histopathological markers are considered very important in terms of showing the health status of the organism, together with other branches of science that provide data [77].

As a result of the intake, absorption and participation of pesticides in the systemic circulation and their effects on a cellular basis, the formation of biochemical and histopathological changes in tissue integrity and the emergence of negative symptoms are provided [7, 78–82]. The effects of environmental pollutants on fish tissues can also be determined by histopathological methods. Gills are especially important biomarkers as they are the first organ to encounter pollutants in the environment [13, 83]. In addition, the liver and kidneys are also target organs for the examination of histopathological and biochemical parameters [84]. In *Oncorhynchus mykiss*, as a result of application of clothianidin at different doses for 21 days, the histopathological state caused by this application in muscle, gill, brain and kidney tissues was examined and necrosis ranging from mild to severe in muscle tissue, atrophy and edema in myocytes, hyaline degeneration in muscle fibers and dissolution in connective tissue between myotomes were determined. In the gill tissue, primary and secondary lamella edema, secondary lamella fusion and hyperplasia, primary lamella hyperplasia, secondary lamella lifting, vasodilation, primary lamella thinning and secondary lamella shortening, and secondary lamella peculiar malformations were reported. Pericellular edema and necrosis, Purkinje cell degeneration, cell infiltration, congestion, gliosis, vascular dilatation and dystrophic changes were detected in the brain tissue. In kidney tissue, glomerular atrophy, decrease in hematopoietic tissue cells, tubular degeneration, and an increase in the number and spread of melanomacrophage centers depending on the increasing dose of clothianidin were observed [26].

The LC50 value (50% mortality) of malathion at the end of 96 hours in *Orthrias angorae* exposed to malathion administration was determined to be 3.0237 mg L−1, and it was reported that the frequency of micronucleus formation in erythrocytes increased due to the increasing dose [85]. In a study with rainbow trout (*Oncorhynchus mykiss*) juveniles, the acute effects of maneb and carbaryl were examined and it was reported that edema and lamellar fusion, epithelial swelling and necrosis were observed in the gill lamellae of the fish [86]. In a study investigating the histopathological effects on the gill and kidney tissues of *Cyprinus carpio* as a result of acute application of deltametrine, necrosis, spills, aneurysm, hemorrhages, edema, and hyperplasia were reported in the gills of fish [87]. Different doses of chlorpyrifos-based termifos pesticide were applied to *Clarias gariepinus* 

#### *An Overview of the Biochemical and Histopathological Effects of Insecticides DOI: http://dx.doi.org/10.5772/intechopen.100401*

*(African catfish)* fish for 5, 10 and 15 days. An increase in white blood cell counts and a decrease in erythrocyte counts and hematocrit levels were observed in fish [88]. In a study in which clothianidin, a neoniconioid insecticide, was applied in rainbow trout for 7 and 21 days, it was reported that clothianidin caused hepatocellular degeneration, focal necrosis areas, sinusoidal dilatation and congestion, fibrous and vacuole formation, mild steatosis and pycnosis in the liver tissue, depending on the increasing dose [17].

In a study in which dichlorvos was administered in rats in a subacute manner [7], enlargement of Bowman's capsule, inflammatory cell infiltration, vascular occlusion, glomerular atrophy, and tubular degeneration areas were demonstrated in kidney tissue obtained from the substance-administered group. On the other hand, glomerular lobulation, tubular degeneration, separation in the basal lamina and inflammatory cell infiltration were observed in the group in which dichlorvos and vitamin E were administered. No significant decrease was observed in the severity and frequency of histological changes compared to the dichlorvos administered group (**Figure 3a–f**).

Carbon tetrachloride (CCI4) is a fumigant used to kill insects in cereals and in a study examining the effects of green tea (*Camellia sinensis*) and parsley (*Petroselinum crispum*) diets against carbon tetrachloride hepatoxicity in albino mice, liver degeneration, cellular infiltration, sinusoidal bleeding focuses, congestion and necrotic areas were observed in the CCI4-administered group. No significant decrease in lesion severity and frequency was observed in the histopathological evaluation obtained from the groups using parsley and green tea separately with CCI4 [89]. It was demonstrated that histopathological changes occurred in tissues at doses of 0.1 and 0.05 mg kg−1 in mice exposed to deltamethrin. Degenerative and vascular changes in the liver, polymorphonuclear cell infiltration and focal necrosis

#### **Figure 3.**

*The effect of dichlorvos (5 mg/kg), corn oil (5 ml/kg) and vit-E (120 mg/kg) either separately or 1 h ago dichlorvos histology of renal section by using hematoxylin and eosin staining (H&E): (a) vit-E group; Gl: Glomeruli, P: Proximal tubule, Dt: Distal tubule, bowman capsule (arrow head), (b, c, d) Dichlorvos group; enlargement in bowman capsule and glomerular atrophy (arrow head), inflammatory cell infiltration (split arrows), BV: Blood vessel, vascular occlusion (asterisks), tubular degeneration (arrows), (e, f) Dichlorvos+vit-E; Gl: Separation in the basal lamina (arrows), tubular degeneration (asterisks), glomerular lobulation (arrow head), magnification: X 400, x 600, (bar: 50* μ*, 100* μ*) [7].*

in hepatocytes were detected. Tubule degeneration and polymorphonuclear cell infiltration in the kidneys, and polymorphonuclear cell infiltration in the peribronchial and perivascular areas of the lungs were reported. Spermatogenic cell degeneration, tubule degeneration, and hyalinization in the seminiferous tubules were demonstrated in the testicles [90]. As a result of malathion application on *Channa punctatus*, the 96-hour LC50 value was determined to be 8.0 mg L−1, sinusoidal dilatation and congestion were observed in the liver, and hypertrophy and pyknotic nuclei were detected in the hepatocytes. In the kidney, histopathological separation of the renal tubular epithelial layer from the basal membrane, vacuolization in the cytoplasm, renal tubule degeneration and necrosis, nuclear pyknosis and hypertrophy were reported in parallel with biochemically high creatinine, urea and BUN values. As the duration of exposure to malathion increased, damage to tissues increased in terms of severity and frequency [91].
